Filters find widespread use in radio transceivers, as shown in FIG. 1. Filters such as those shown in FIG. 1 are used to limit noise while attenuating potentially interfering signals as well as spurious signals. Most communication systems require RF filters with sharp frequency responses (i.e., notches) that make monolithic integration difficult. As a result, RF filters typically use bulky technologies, such as surface acoustic wave (SAW) or ceramic resonators. It would therefore be desirable to find methods and apparatus to provide more flexible and more readily integratable RF filters, as well as provide other advantages.